I've been reading about the diet and the concpept is that it is designed to retrain your body to burning layers of fat that are nor normally burned.
Once you do the protocol and follow the mainenance plan, you should not have abnormal problems with gaining weight in the future. The maintenance is no carb, but the life time program is low carb and they say you can eat normal amounts of food without regaining the weight. Hard to say...but it sounds really interesting. Many are doing it now and I suspect in a year or two, we'll know much more.